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Tuesday, July 9, 2013

How to make volumetric lights and fog in V-ray for Maya (God rays)

This is not that hard to accomplish but no one ever writes tutorials on it! How frustrating... here is how to do it.

NOTE: The fog effect will be affected by the scale of your scene so probably best to work in real world scale. This tutorial was done at a relatively small scale so you may need to adjust your numbers some from my values.

First set up the scene for you shafts
of light. In this case we are going to make a window with
sunlight flowing in the window.

I've created a simple hollow box with a
cut out in the wall for the window.

Create an area light top create
menu>lights>v-ray rect light. and position it in your window
to give you some soft ambient light filtering int other room.

Position your spot light so that it
some distance away from your window and focused in on it.
Narrow the angle on the light so that it's literally spotted
right on the window.If it helps you can select the light in
the outliner and then in your viewport Panels>Look
through select to aim it

right in line wit the opening. Make
sure to turn on "Use Raytrace Shadows" in your spot
lights settings.

You should have something like this we can see the spot light gently hitting the floor.

The create render node screen comes up.
Type "fog" in the quick search box at the top option to
select Vray Environment.

Now press the arrow next to the
Environment Shader to see the settings for your fog effect. Let's do
a test render.

At the default settings the scene may
be very dark or even render black. This is because of how
thick the fog is.

Now you could turn the fog density
down, but then you will lose your "shafts effect" so
let's instead turn the lights up.

First turn your area light at the
window up to 3.

Now let's turn our spot light up to
300.

And now we finally have shafts
beginning to show up. Everything is pixeled though so go back
to your fog settings.

Render settings>V-ray
Tab>environmental drop down. Press the right arrow. And turn up the Subdive
setting on your fog to 32. Then turn the Shadows rays up on
your area light and spotlight to 24. To smooth things out.

This should give you a good starting
place for creating volumetric light effects on your own.
Here is a great